If ConTeXt appears to behave in a counterintuitive way, chances are that it’s actually your intuitions that lack calibration.
If you add the option page=yes
to a heading setup, this
will cause ConTeXt to break the page.
Ordinarily this works as expected, unless, however, the heading
immediately follows a previous section with no text in between.
The rationale behind this is that consecutive headings are conceived of
collectively as one single structural element.